Scale and Gauge

Scale, Gauge and Off-Scale

These days, we take scale pretty much for granted. The past hundred years
have seen the pervasive development of standardization among most miniature
hobbies, from model railroading to military miniatures to collectible diecast
automobiles. Today, there are a handful of "standard" scales for any given
hobby.

What exactly is scale? SCALE is the size relationship of a model to the real
world. Usually, it is expressed in fractions. Thus, a scale of 1/24 has
dimensions that are a twenty-fourth the height, length, width and depth of
its real-world counterpart. Another way of doing this is 1:24, or "one to
twenty-four". That means that one foot (or inch or millimeter) of real measure
equals twenty-four of the miniature. (In America, this is generally measured
by the foot.)

Another way to express scale in America is by the scale foot. So it is that
"quarter inch scale" means a scale in which 1/4 inch equals one real-world
foot - in other words, 1/48. We sometimes here "half-inch scale" (1/12),
"quarter inch scale" (1/48) and "three-sixteenths inch scale" (1/64th) used
by hobbyists.

A measure popular among military miniature hobbyists is that of the height
of an average figure in a particular scale. It originated in Europe. This
is normally measured in millimeters. For instance, "54mm scale" refers to
1/32, where the height of an average standing soldier would be 54mm, or 2
1/4 inches tall. (On rare occasion, one may hear inch measurements rather
than millimeters). Figure height was originated by people who collected the
soldiers themselves, and those who used miniatures in war games. The dimensions
of other things - scenery, buildings, vehicles, etc. - were incidental to
those of the miniature soldier.

Fraction and scale foot measurements tell us that those using them are focused
on the dimensions of objects and distances, whereas those whose main concern
is a humanoid miniature rely on figure height measures.

The model railroading hobby used letters to describe scale. Widespread
standardization among the various rail-scales allowed for use of a simple
letter code. Originally, the code referred more to gauge - the distance between
rails on a given piece of track - than to scale. Thus O gauge meant model
trains that used track whose outside rails were 1 1/4 inch apart. It's no
coincidence, then, that HO would mean "half-O", for purposes of gauge. As
interest in scale accuracy grew among toy train fans, the letters came to
represent a scale moreso than a track width. Thus, O scale is 1/48 - in other
words, a train that uses track 1 1/4 inches apart would be 1/48 scale. Scale
and track width soon were distinguished. The plain letter denotes a scale
and its gauge, while other track gauges within that scale get special attention.
For instance, "HON3" means HO scale, using a narrow gauge track. This track
is 3 scale feet wide, as opposed to the normal four foot- eight inches of
standard railroad gauge. The N tells us that this is narrow gauge. HON30
is different, meaning narrow gauge of 30 inches. By the way, HON30
is the same track gauge as the smaller N scale! As trains went from toy to
scale model, thus the letter code changed from gauge to scale.

Different hobbies have their own particular scales, and not all of them equate
with one another. Standardization, common in model railroading, is not an
absolute in other miniature hobbies. Keep in mind that other hobbies have
a different focus. Military figures stress the human dimensions, for instance,
as opposed to the scale of objects and distances in model railroading. Sometimes
it is like the old saw about what came first: the chicken or the egg? In
model railroading, objects - trains and track - came before miniature people.
For toy soldier collectors, the people came before the objects.

Track Gauges by Scale

Gauge is the distance between the outer rails. Scales listed below
are based on a real-life gauge of 4 foot 8 inches.

Name of Scale

Inches

Millimeters

Scale

Standard

2 1/8"

53mm

#1 - G

1 3/4"

45mm

1/32 - 1/29 (Narrow: 1/20.3, 1/22.5, 1/24)

O*

1 1/4"

31.8mm

1/48 (1/43.5 in UK)

S

7/8"

22.2mm

1/64

OO (US)

3/4"

19mm

1/76

HO

5/8"

16.5mm

1/87.1

TT

15/32"

12mm

1/120 (US)

N (OOO)

3/8"

9mm

1/160

Z

1/4"

6.52mm

1/220

O-3/16 **(O27)

1 1/4"

31.8mm

1/64

* Obviously, in 1/48, real-life gauge would be 5 foot. That anomaly
is overlooked by most O gaugers

** The original O27 scale trains were 1/64 scale models running on O tricks
and track.

The Scales and Their Adherents

Let's look at a wide range of popular scales, who uses them, and why. Normally,
model railroaders fall back on their letter code to denote a scale. Miniature
soldier hobbyists use the figure height, while builders of other types of
models tend to rely on fractions. Model railroaders involved in the larger
scales - S and higher - will also use the scale foot measure.

Fractions:

A general rule is that when fractions are used to denote scale, the accuracy
of scale is reliable. Naturally, this is a generalization and does not bear
on every maker or model.

1/6 scale refers to models where one real foot is represented by two inches.
Thus, a six-foot figure would be twelve inches tall. 1/6 is used mainly by
those involved in large flying models or large human miniatures.

1/12 is a scale where one foot is represented by one inch. Thus, the average
miniature human is about six inches tall. Again, favored for large models.

1/18 scale is popular among collectors and builders of model automobiles.

1/20 and 1/20.3 are used by some American G/ #1 gauge makers for narrow gauge.

1/22.5 is G Scale, a German narrow-gauge version of #1 gauge.

1/24 is also popular with the model automobile hobby, and with slot car racers.
It is used by some G / #1 makers

1/29 is the scale of some locomotives using G gauge track. G varies - some
use it for 1/29 scale. while others use a 1/32 dimension.

1/32 scale is popular among builders of model military vehicles and toy soldier
collectors. It is also used by some slot car racers. 1/32 is the height of
the "standard" toy soldier. It is the same as the 54mm - 2 1/4 inch scale
used by miniature figure collectors.

1/35 is another scale for military model builders. Its human miniature figures
stand 50 to 51mm tall.

1/40 is occasionally encountered among automobile and military vehicle models.
The average height of a human figure in this scale is 45mm. Many recent toy
soldier "clones" are 45mm tall.

1/43 is a scale used by diecast model car collectors. Some cars in this scale
are sold as O gauge miniatures. Actually, the scale varied between pure 1/43
and 1/48.

1/48 is popular with model railroaders, model airplane hobbyists and some
diecast car collectors. Also known as "quarter inch (1/4 inch) scale" or
"O scale", it has a small following among military vehicle model collectors.
The height of the average figure is 1 1/2 inches, or 40 mm. Among wargamers,
there's a relatively small contingent who use 40mm figures.

1/50 is another diecast car scale. It is often marketed as O scale, and in
fact scale accuracy of these cars can range from 1/45 to 1/48 to 1/50.

1/64 is popular among diecast car collectors and miniature war gamers; it
is regaining its popularity among model railroaders as "S" scale. The height
of the average person in 1/64 is 30mm, or about 1 1/8 tall. For many years,
"30mm" was the major wargaming scale. 30mm scale was supplanted by the profusion
of 25mm figures in the early 1970s.

1/72 scale is popular among model airplane builders, small-scale military
model makers and some wargamers. A 1/72 scale figure is 25mm, or 1 inch tall.
The scale was originally the mainstay of model airplane buffs. It has no
precise counterpart in model railroading.

1/76th scale was the mainstay of small-scale military model builders, and
is the true scale of the kits made by Airfix, Matchbox, Fujimi, and a few
others. It has been marketed as 1/72 since the late 80s, but this in incorrect.
1/76 is also OO scale, a European phenomenon which emerged in the 1930s but
was overshadowed by HO and this fell into decline. It is sometimes called
20mm scale, because the average height of figures introduced by a major maker
in the 1950s and early 1960s was that height. Actually, 20mm figures are
HO scale! As you can see, 1/76 had its problems with accuracy across-the-board.

1/87 scale is the most popular scale, used by model railroaders, small-scale
military modelers, wargamers, slot car racers and diecast car collectors.
Known to the rail hobby as HO and by war gamers as 20mm, it has more support
than any other scale. This is due almost entirely to the rail folks, who
assiduously worked to standardize the scale back in the 1940s and 1950s.

1/90 is an obscure scale used by some Central European manufacturers of model
military vehicles. Today, it is sold as HO

1/100 scale is an off-scale for model builders. 3mm scale, also known as
'English TT' or '3mm scale', technically uses a scale of 1/106. Some
round it down to 1/100. Several companies make 1/100 scenery products
for architectural use, and these are also used by 3mm Scalers.

1/120 is another model scale. The founder of TT, an American engineer, used
1/10 inch as a scale foot. (Tenths of inches are used in American
engineering.) For model railroaders, it is known as TT, for Table Top.
TT was originally meant to be the next smaller scale after HO. It never caught
much of a following, although it was popular in Eastern Europe during the
Soviet era. (The model train makers in East Germany made TT.)

1/144 is a small scale used mainly by model airplane and model boat builders.
Occasionally, 1/144 vehicles find their way onto N scale layouts. The off-scale
is also employed for space ships and scale model rockets.

1/160 is very popular among model railroaders as N scale. Its small size
and fine detail make it the scale of choice for folks who want huge railroads
or who have limited space.

1/220 is the new Z scale, which is intended to be the smallest railroad scale.
A European import, it has a small following in North America.

Scale foot:

Quarter Inch scale denotes O gauge and 1/48 scale

Three-sixteenths scale means 1/64, or S scale

3 inch scale actually denotes a scale where the average human figure is 3
inches, or 70mm tall.

2 1/4 inch scale is the same as 1/32 and 54mm scale, referring as it does
to the height of the average human figure.

Millimeters:

While millimeter scale would seem accurate, the fact is that makers who use
this measure of scale can vary. We have seen numerous cases of figures marketed
as one size which are actually closer to the next higher - or lower- scale.
That's not a problem for wargaming or some military modelers, but for model
railroaders it can be a major annoyance!

120mm scale is used by miniature figure builders, and denotes --- scale.
The average figure is almost 5 inches tall.

90mm scale is favored by miniature figure collectors because of its large
size and greater detail. The average figure is almost 4 inches tall

70 and 75mm scale are for military figures, these being 3 inches tall.

60mm scale is a toy soldier scale, denoting plastic figures about 2 1/2 inches
tall. It is rarely used for serious scale modeling. The 60mm figures were
plastic toy soldiers designed between 1950 and 1975. Some are still being
manufactured.

54mm scale is the standard toy soldier scale, being 1/32. It is also one
of the scales used in G scale, the other being 1/29.

50mm / 52mm scale is 1/35, and is a popular size for military miniatures
and plastic toy soldiers.

45mm is a popular size of current toy soldiers. It equals 1/40 scale.

40mm is actually 1/48 scale, or O. 40mm figures are made by Elastolin, Starlux
and other European makers for use in wargames. (Civil War figures from these
makers are popular for use in 1860 - 1870 era model railroads!)

35mm is an off-scale used by a rare few suppliers of wargame figures.

30mm scale is also 1/64, or S. It was the major wargame scale until the field
was overrun by makers of 25mm figures in the early 1970s.

25mm figures are exactly one inch tall, and are 1/72 scale. The most popular
wargaming figures, the main scale for model airplanes.

20mm figures, sometimes mistakenly sold as 1/76 scale, are actually HO scale.
Because HO has such wide support, they're often used by wargamers as well
as model railroaders.

15mm scale figures are a relatively recent development, made for wargames.
They can be used in TT and N scale layouts.

10mm figures are more the latest wargame scale, and can be used in N scale
layouts.

Letter Codes

The letter codes used to denote scale for model railroaders have an additional
benefit. Because model railroad scales are well -standardized, you will generally
find that items sold as a particular scale are accurate in dimensions. The
only exceptions are O27 and O semi-scale trains - toy trains where scale
is not the main concern - and some older off-scales like TT and OO.

Standard Gauge: the original Lionel trains were massive, with 2 1/2 inch
gauge tracks. They were toys, so scale gave way to other considerations.
Standard gauge trains are very rare today.

G scale has recently emigrated from Europe, Used in garden railways, its
scale ranges from 1/20 to 1/32. Major makers are Aristo-Craft, USA Trains,
Bachmann and LGB. Not bad if you can run trains in the backyard, but too
big for most indoor use.

O Gauge / Scale was introduced by Lionel as an alternative to Standard Gauge.
Technically, it is 1/48 scale. In fact, many O gauge trains are "semi-scale",
with some dimensions truncated to allow use on 31" diameter track.

O27 is a peculiar way of semi-scaling O gauge to fit a 27" diameter curve
track. O27 trains are slightly smaller than O. Originally, Gilbert introduced
the idea of a 3/16 S scale train running on O gauge trucks and track. The
idea was picked up by Marx, who specialized in it, and by Lionel. Lionel
later dropped the 3/16 idea, but retained the smaller scaling for O27 trains.
If you're a scale modeler, it makes a difference. If not, you'll have no
problem mixing O and O27 trains.

S scale, promoted heavily by the A.C. Gilbert company, is 1/64 scale. It
was very popular up until the early 1960s, being the biggest competition
to Lionel's O and O27 trains. S tends to be more accurate, insofar as scale.
It is slowly regaining popularity in North America, as S offers opportunities
for more detail than HO without the large size of O and O27.

OO is 1/76 scale. In some cases (common British practice today), OO and HO
used the same track. OO was more popular during the 1930s, but was eventually
eclipsed by the growing popularity and affordability of HO. A very small
number of model railroaders continue to support the scale in the US.

HO is 1/87 scale. Favored by a small group of serious model railroaders in
the 1930s, it was developed as a scale rather than just a gauge. The realm
of craftsman kits and scratchbuilders, HO competed with OO as the small scale
of the day. It won out, and by the late 1950s enjoyed a large following thanks
to its smaller size and lower cost than comparable O and S scale trains.
HO has the widest support, insofar as trains, accessories, scenery, etc.

TT (Table Top) is more properly 1/120 scale. It was intended to be small
enough for those with limited space. Though it has a few followers today,
and was the main scale in Warsaw Pact countries, TT has pretty much fallen
by the wayside. A small group of TT fans keeps the scale going in the
US.

3mm Scale, called 'English TT' by some uses a scale foot of....3mm! It
is technically 1/106 scale, some claim it is 1/103, and many narrow it down
to 1/100

N scale was imported from Europe in the late 1960s. It was not always "scale,"
as the manufacturing capabilities and materials available then didn't allow
for perfect miniaturization. Sometimes the old N trains resembles a tiny
version of "semi-scale." Time won out, and the quality of N improved drastically.
Today, N trains are scale and have exquisite detail. Though intended for
folks with limited space to devote to model railroading, N scale has become
an institution of its own and is also enjoyed by folks who want massive model
railroads, regardless of space.

Z scale is the newest European import, being 1/220 scale. The tiny size allows
a more elaborate railroad in a smaller area. It has a small following in
North America. The gauge is only 1/4" (6.5mm!)

O Gauge versus O Scale

Hi-rail, 2-rail, AC and DC

Though classic toy train makers like Lionel, K-Line and MTH manufacture both
scale and semi-scale trains, they are considered to be O gauge rather than
pure scale. Classic trains run on three-rail track. Let's face it, friends:
does that track look like the rail one might see on a real railroad? Even
the new scale-type track offered by Atlas doesn't look exactly real. Real
railroads use two rails, not three. Besides, most O gauge rail has little
resemblance to real rail in shape or dimensions.

Then there's the matter of curves. O gauge trains can make it around a 31
inch curve. Real trains use wider curves, and so something isn't scale here!
Or is it?

Though the Lionel Heritage series and Kline Classic Scale are 1/48 models
in every regard, and some require wider-radius curves, they're still running
on 3-rail track. And they happen to use Alternating Current, or AC.

A different kind of O trains are Direct Current (DC) powered, two-rail trains.
These trains require a lot more room for the wider curves, have different
couplers and are more like enlarged HO trains than classic O gauge. They
don't have all the nice operating accessories, neither. DC O scale has a
small following among scale model railroad buffs who have the space and money
for that kind of operation. (Toy train buffs call those fellows "rivet
counters.")

The difference? Those of us who have three-rail, hi-rail O gauge have more
fun.

Narrow Gauge???

In case you don't know about Narrow Gauge but were afraid to ask.... In the
late 1800s, railroad gauge was standardized to 4 foot, 8 inches between rails.
Some US railroads had a six foot gauge back then, and it made transfer from
one railroad to the other a problem.

But some railroads had another problem altogether: limited space for a
right-of-way. These include logging, mining, and mountain railroads whose
routes took them through tight curves, up narrow mountain ledges and through
difficult forests. The easiest way to deal with it was to have a narrower
gauge track. A large part of the Denver and Rio Grande Railroad was narrow
gauge, for instance, because of its routes through the Rocky Mountains and
its mining operations. The distance between rails would be anywhere from
two to three and a half feet.

In model railroading, there are folks who specialize in narrow gauge. They
denote their specialty by first giving the actual scale, and then the track
width. Thus, HON3 means HO scale (1/87) using a 3 foot gauge. By coincidence,
HON3 gauge is the same as the gauge of N track! And ON3 (O gauge, narrow
3 foot gauge) is the same width as HO track. Thus some narrow gauge is like
using larger trains on smaller track.

No, it isn't as simple as buying HON30 trucks for your trains, and then setting
up N scale track to run them. Not if you want to be scale, that is! The ties
on N track are okay for N scale, but would be too small for HO. Thus, you'd
first have to replace the N ties with slightly thicker ones in order to have
a true scale appearance. And that's just the beginning.

Why do people get into narrow gauge? They have many reasons, but a lot are
the kind of folks who get a thrill in making some things on their own. They
have to make or improvise parts, since narrow gauge doesn't have the same
wide support as standard gauge. For that reason, narrow gauge layouts tend
to be very individual, very unique, and they have a high degree of creativity.
(I've never seen a narrow gauge model railroad that was dull.) If you enjoy
making your own, you might want to look into narrow gauge. (If you ever need
something made and you have a narrow guage fan around, you're in luck).

Scale Standardization: Is the Scale True to Scale?

One cannot make the assumption that every scale item is true to scale in
every way. Experienced modelers know that scale can be a matter of
interpretation. One manufacturer's 1/35 might not be another's. We've
run across this many times. Army men have rarely been paragons of perfect
scale. Even the cast metal miniatures tend to differ, with one company's
25mm figures resembling another's 30mm troops. Therefore, this chart
is far from perfect. Some of the dimensions are based on the most common
interpretation rather than pinpoint accuracy.

The original figures from Airfix (Infantry, German Infantry, Cowboys,
Indians, Civilians, Colour Guards, etc.) were closer in size to HO figures
than the standard 25mm scale. Starting in the late 60s, the Airfix
small figures got larger. This is but one example of "scale / not really
scale." The toy soldier and miniature hobby has not made great strides
in standardizing scales, which is why different manufacturers and even individual
kits can vary.

The model railroad hobby has done tremendous work in standardizing N, HO,
S and O scale. Initially, these scales only denoted the "gauge," which is
the distance between the tracks. As the hobby grew, it eventually developed
an "establishment" which set to standardizing everything else in the years
following World War II. With the backing of large organizations such
as the National Model Railroading Association, the popular scales were given
a very tight set of standards, right down to millimeters per scale feet!
Less popular scales such as Standard, TableTop (TT) and OO had fallen
through the cracks. They were not given the intense degree of scale
accuracy and standardization that had been showered on N, HO, S and O.
Indeed, because toy trains like Lionel and K-Line use the O track width
but do not adhere strictly to 1/48 scale, they are commonly called "O gauge."
"O Scale" denotes trains which are a perfect 1/48 scale in all dimensions.

G Scale, a relative newcomer, was originally 1/22.5 narrow gauge using #1
gauge track. In practice, G / #1 gauge is somewhere between 1/20 and
1/32 scale, depending mainly on the individual manufacturer. The model
railroad establishment has standardized G's track gauge and related dimensions,
but not the precise scale. The original gauge is the old #1 at 1 3/4
inches, or 45mm. The 'official' scale, using #1 gauge as standard,
is 1/32. Some US makers use 1/29, while the narrow gaugers run between1/24
and 1/20. LGB, who resurrecteded #1 as narrow gauge, denotes G as 1/22.5.
(For more information on G / #1, click here)

For years, hobbyists using the 1/72 - 1/76 scale have filled in the gaps
with HO scenery and models (i.e. ROCO MiniTanks and Roskopf's 1/87 - 1/90
scale vehicles). Model soldier scales have never been standardized,
so as to allow across-the-board availability of perfect scale scenery
and accessories. The same is true in larger scales. For instance,
it was common for diorama makers in the early 70s to mix 1/32 and 1/35 scale
vehicles, troops and accessories. I have seen 1/35 scale kits that
are virtually indistinguishable in scale from 1/32 kits!

Our chart reflects this, insofar as those scales which do not have strict,
regulated standards. Only the N, HO, S and O railroad scales are strictly
determined. 1/100, 1/120, 1/144, 1/76 - 1/72 and others tend to fluctuate.
In effect, one company's 1/144 is not another's. Mininature soldier
30mm scale is not always perfect 1/64. (It coule be anything from perfect
1/72 to perfect 1/60th!) Keep that in mind as you use this chart. At
best, non-standardized railroad scales are an approximation rather than an
absolute.

Note: MM = 1 Scale Ft means that so many millimeters in a given scale
would equal one scale foot.